Colonic diverticula are protrusions of the mucosa through the outer muscular layers, which are usually abnormally thickened, to form narrow necked pouches. Diverticular disease of the colon covers a wide clinical spectrum: from an incidental finding to symptomatic uncomplicated disease to diverticulitis. A quarter of patients with diverticulitis will develop potentially life-threatening complications including perforation, fistulae, obstruction or stricture. In Western countries diverticular disease predominantly affects the left colon, its prevalence increases with age and its causation has been linked to a low dietary fibre intake. Right-sided diverticular disease is more commonly seen in Asian populations and affects younger patients. Its pathogenesis and relationship to left-sided diverticular disease remains unclear. Diverticular disease of the colon is a significant cause of morbidity and mortality in the Western world and its frequency has increased throughout the whole of the 20th century. Since it is a disease of the elderly, and with an aging population, it can be expected to occupy an increasing portion of the surgical and gastroenterological workload. It is uncertain what symptoms uncomplicated diverticular disease gives rise to: there is an overlap with irritable bowel syndrome. Diagnosis is primarily by barium enema and colonoscopy, but more sophisticated imaging procedures such as computed tomography (CT) are increasingly being used to assess and treat complications such as abscess or fistula, or to provide alternative diagnoses if diverticulosis is not confirmed. Initial therapy for uncomplicated diverticulitis is supportive, including monitoring, bowel rest and antibacterials. CT is used to guide percutaneous drainage of abscesses to avoid surgery or allow it to be performed as an elective procedure. Surgery is indicated for complications of acute diverticulitis, including failure of medical treatment, gross perforation, and abscess formation that cannot be resolved by percutaneous drainage. Complications of chronic diverticulitis (fistula formation, stricture and obstruction) are also usually treated surgically. However, the indications for, and the timing and staging of operations for diverticular disease are often difficult decisions requiring sound clinical judgement. Factors such as the number of episodes of inflammation, the age of the patient, and his/her overall medical condition play a role in determining whether or not a patient should undergo surgical resection. Laparoscopic surgery may be associated with less pain, less morbidity and shorter hospital stays, but its exact role is yet to be defined. Diverticular disease of the colon is the most common cause of acute lower gastrointestinal haemorrhage, which can be massive. Although the majority of patients stop bleeding spontaneously, angiographic and surgical treatment may be required, while the place of endoscopic haemostasis remains to be established.